WPF 斜角border

最近看了一些科技感UI设计，其中很多的按钮都不是常见的圆角边，而是斜角边。查了一下，wpf中好像没有现成的斜角border，网上也没搜到现成的，于是自己写了点时间做了一个，写的较简单，有一些bug（主要是没有去管一些极值情况），但也基本可用了。

下面与大家分享一下代码：

先上效果：

前台代码：

    <Window.Resources>
        <Style TargetType="{x:Type local:BeveledBorder}">
            <Setter Property="Background" Value="#90000000" />
            <Setter Property="BorderBrush" Value="Black"/>
            <Setter Property="BorderThickness" Value="2"/>
            <Setter Property="Margin" Value="2" />
            <Style.Triggers>
                <Trigger Property="IsMouseOver" Value="True">
                    <Setter Property="Background" Value="#90FF0000"/>
                </Trigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>
    <UniformGrid Rows="1" VerticalAlignment="Center" MinHeight="50">

        <local:BeveledBorder CornerRadius="10,0,10,0">
            <TextBlock Text="123" HorizontalAlignment="Center" VerticalAlignment="Center"/>
        </local:BeveledBorder>

        <local:BeveledBorder CornerRadius="10,10,10,10"/>

        <local:BeveledBorder CornerRadius="10,20,10,20"/>

        <local:BeveledBorder CornerRadius="0,15,0,15"/>

        <local:BeveledBorder Width="40" Height="40"
                             CornerRadius="10,10,10,10"/>

    </UniformGrid>

后台类：

    /// <summary>
    /// 斜角Border
    /// </summary>
    class BeveledBorder : Decorator
    {
        public Brush BorderBrush
        {
            get { return (Brush)GetValue(BorderBrushProperty); }
            set { SetValue(BorderBrushProperty, value); }
        }

        public static readonly DependencyProperty BorderBrushProperty =
            Border.BorderBrushProperty.AddOwner(typeof(BeveledBorder), new PropertyMetadata(Brushes.Transparent, CommonPropertyChanged));

        public Thickness BorderThickness
        {
            get { return (Thickness)GetValue(BorderThicknessProperty); }
            set { SetValue(BorderThicknessProperty, value); }
        }

        public static readonly DependencyProperty  BorderThicknessProperty = 
            Border.BorderThicknessProperty.AddOwner(typeof(BeveledBorder), new PropertyMetadata(new Thickness(), CommonPropertyChanged));

        public Brush Background
        {
            get { return (Brush)GetValue(BackgroundProperty); }
            set { SetValue(BackgroundProperty, value); }
        }

        public static readonly DependencyProperty BackgroundProperty =
            Control.BackgroundProperty.AddOwner(typeof(BeveledBorder), new PropertyMetadata(Brushes.Transparent, CommonPropertyChanged));

        public CornerRadius CornerRadius
        {
            get { return (CornerRadius)GetValue(CornerRadiusProperty); }
            set { SetValue(CornerRadiusProperty, value); }
        }

        public static readonly DependencyProperty CornerRadiusProperty =
            Border.CornerRadiusProperty.AddOwner(typeof(BeveledBorder), new PropertyMetadata(new CornerRadius(), CommonPropertyChanged));


        private static void CommonPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            (d as BeveledBorder)._isrendersizechanged = true;
            (d as BeveledBorder).InvalidateVisual();
        }

        protected override void OnRender(DrawingContext drawingContext)
        {
            base.OnRender(drawingContext);

            if (_isrendersizechanged)
            {
                _isrendersizechanged = false;
                UpdateGeometry(RenderSize);
            }

            Pen pTop = new Pen(BorderBrush, BorderThickness.Top);
            drawingContext.DrawGeometry(Background, pTop, _currenGeometry);
        }

        protected override void OnRenderSizeChanged(SizeChangedInfo sizeInfo)
        {
            base.OnRenderSizeChanged(sizeInfo);
            _isrendersizechanged = true;
        }

        private void UpdateGeometry(Size nsize)
        {
            if (_currenGeometry == null)
            {
                _currenGeometry = new PathGeometry();
                _currenGeometry.Figures.Add(new PathFigure());
                _currenGeometry.Figures[0].IsClosed = true;
            }
            else
            {
                _currenGeometry.Figures[0].Segments.Clear();
            }

            if (CornerRadius == null)
            {
　　
                _currenGeometry.Figures[0].StartPoint = new Point(0, 0);

 　　　　　　　　　  _currenGeometry.Figures[0].Segments.Add(ToLineSegment(new Point(nsize.Width, 0)));
                  _currenGeometry.Figures[0].Segments.Add(ToLineSegment(new Point(nsize.Width, nsize.Height)));
                  _currenGeometry.Figures[0].Segments.Add(ToLineSegment(new Point(0, nsize.Height)));

            }
            else
            {
                _currenGeometry.Figures[0].StartPoint = new Point(CornerRadius.TopLeft, 0);

                if (CornerRadius.TopRight <= 0)
                {
                    _currenGeometry.Figures[0].Segments.Add(ToLineSegment(new Point(nsize.Width, 0)));
                }
                else
                {
                    _currenGeometry.Figures[0].Segments.Add(ToLineSegment(new Point(nsize.Width - CornerRadius.TopRight, 0)));
                    _currenGeometry.Figures[0].Segments.Add(ToLineSegment(new Point(nsize.Width, CornerRadius.TopRight)));
                }

                if (CornerRadius.BottomRight <= 0)
                {
                    _currenGeometry.Figures[0].Segments.Add(ToLineSegment(new Point(nsize.Width, nsize.Height)));
                }
                else
                {
                    _currenGeometry.Figures[0].Segments.Add(ToLineSegment(new Point(nsize.Width, nsize.Height - CornerRadius.BottomRight)));
                    _currenGeometry.Figures[0].Segments.Add(ToLineSegment(new Point(nsize.Width - CornerRadius.BottomRight, nsize.Height)));
                }

                if (CornerRadius.BottomLeft <= 0)
                {
                    _currenGeometry.Figures[0].Segments.Add(ToLineSegment(new Point(0, nsize.Height)));
                }
                else
                {
                    _currenGeometry.Figures[0].Segments.Add(ToLineSegment(new Point(CornerRadius.BottomLeft, nsize.Height)));
                    _currenGeometry.Figures[0].Segments.Add(ToLineSegment(new Point(0, nsize.Height - CornerRadius.BottomLeft)));
                }

                if (CornerRadius.TopLeft > 0)
                {
                    _currenGeometry.Figures[0].Segments.Add(ToLineSegment(new Point(0, CornerRadius.TopLeft)));
                }
            }
        }

        private LineSegment ToLineSegment(Point pt)
        {
            return new LineSegment(pt, true);
        }


        private PathGeometry _currenGeometry = null;
        private bool _isrendersizechanged = true;
    }